Counterbalance mechanisms are often used to bias a first component relative to a second component. For example, a vehicle may include a counterbalance mechanism for biasing a hood or a truck deck lid relative to a vehicle structure. The counterbalance mechanisms provide a biasing force which helps or assists in moving the first component relative to the second component. The biasing force from the counterbalance mechanism reduces the force that a user must apply to lift or move the first component relative to the second component.
Counterbalance mechanisms typically include a spring, which is used to provide the biasing force of the counterbalance mechanism. One type of spring used in counterbalance mechanisms is a spiral spring. A spiral spring may alternatively be referred to as a clock spring. Spiral springs include a flat strip of spring steel that is coiled up around an axis in a shape of an Archimedean spiral to define the plurality of coils. An Archimedean spiral may be defined as the locus of points corresponding to the locations over time of a point moving away from a fixed point with a constant speed along a line which rotates with constant angular velocity about a center.
When spiral springs are loaded, i.e., wound, the coils urged to one side of the winding axis, disposing the spiral spring in eccentric position about the winding axis. When disposed in the eccentric position, one or more of the coils contact the adjacent coils on one side of the widening axis, thereby introducing a friction force between the contacting coils of the spiral spring. The friction force caused by the contacting coils reduces the efficiency of the spiral spring.